Stop obsessing about what you eat or drink as the secret of a long and healthy life may actually lie in your genes, scientists have suggested after mapping the entire DNA sequence of the world’s oldest woman and discovering that her brain showed no sign of dementia.

Nor did she suffer from any other damage associated with old age such as hardening of the arteries.

The woman, a Dutch, was 115 when she died of a stomach tumour in 2005.

The findings have led researchers to believe that it was perhaps her genes that protected her against conditions relating to ageing.

“We know that she’s special, we know that her brain had absolutely no signs of Alzheimer’s. There must be something in her body that is protective against dementia. We think that there are genes that may ensure a long life and be protective against Alzheimer’s,” said Dr. Henne Holstege, of the Department of Clinical Genetics at the VU University Medical Centre in Amsterdam, who led a team of Dutch scientists that pieced together the woman’s DNA sequence.

Scientists said the study could help understand the “biology of ageing” but warned against rushing to conclusions.

Dr. Jeffrey Barrett of the Sanger Centre in Cambridge, U.K., said the DNA sequences of “hundreds of thousands of people” would have to be studied before reaching any firm conclusions about the “underlying biology of living a long, healthy life”.

“Sequencing the genome of the world’s oldest woman is an important starting point to understand how DNA variation relates to the process of having a long, healthy life. But in order to really understand the underlying biology of living a long, healthy life, we will need to look at the DNA sequence of hundreds or thousands of people,” he told the BBC.

The team behind the study did not disclose the identity of the woman describing her only as “W115” and the oldest person to have her genes mapped. But the Times gave her name as Ms. van Andel-Schipper who was born in 1890 claiming that it was able to establish her identity on the basis that “only one Dutch person is known to have lived to 115”. A year before her death, she attributed her “long, healthy life to a daily portion of herring” but science may have a different explanation.